JN0-106 User Interfaces Practice Test 3 — 15 Questions

Question 1

Refer to the exhibit. Based on the output, which statement is true?

Accepted Answer

The router hostname is router1.. The output shows the system prompt ending with 'router1>', which indicates the hostname is set to 'router1'. In Junos, the CLI prompt format is 'hostname>', so this directly confirms the router hostname. Option D is correct because the prompt explicitly displays 'router1' as the active hostname.

Answer

The admin user has read-only access.

Answer

The interface ge-0/0/0 has been disabled.

Answer

The root password is stored in plaintext.

Question 2

You are a network administrator for a large service provider. You have a Juniper MX960 that serves as a core router. The router uses a configuration with many apply-groups to streamline management. Recently, you added a new apply-group for interface-specific policies. After committing, several interfaces stopped passing traffic due to incorrect policy application. You need to quickly revert to the previous configuration without losing other valid changes made by other engineers in the same commit. The previous configuration is stored as rollback 1. However, rollback 1 contains configuration that does not include the new apply-group but also includes other valid changes from the last commit. You want to restore the configuration to exactly the state before the last commit (the rollback 1 state). Which command should you use?

Accepted Answer

load override rollback 1 and commit. 'load override rollback 1' replaces the entire candidate configuration with the exact contents of rollback 1, which is the state before the last commit. This allows you to revert the problematic apply-group change while preserving all other valid changes that were part of that same rollback snapshot. A subsequent 'commit' then activates this configuration, effectively undoing only the last commit without affecting earlier valid changes.

Answer

rollback 0 and commit check

Answer

rollback 0 and then commit

Answer

request system configuration rescue save and then load rescue

Question 3

A network engineer is troubleshooting a BGP session that is not establishing. They want to see the BGP configuration details for peer 10.0.0.1. They type 'show configuration protocols bgp group external peer 10.0.0.1' but receive 'error: syntax error'. They are in operational mode. What is the most likely issue?

Accepted Answer

The keyword 'peer' should be 'neighbor'.. In Junos OS, the correct keyword to reference a BGP peer in operational mode commands is 'neighbor', not 'peer'. The command 'show configuration protocols bgp group external neighbor 10.0.0.1' would display the configuration for that specific peer. Using 'peer' causes a syntax error because Junos does not recognize that keyword in this context.

Answer

The peer IP 10.0.0.1 is not configured on the device.

Answer

The command should be 'show configuration protocols bgp group external | match 10.0.0.1'.

Answer

They need to enter configuration mode first.

Question 4

Which two commands can be used to view the candidate configuration in set format? (Choose two.)

Accepted Answer

show | display set (in configuration mode). Option C is correct because in Junos configuration mode the pipe command 'show | display set' renders the candidate configuration in set format, showing each statement as a full 'set ...' command line. Option D is correct because from operational mode 'show configuration | display set' also displays the candidate configuration in set format, since 'show configuration' reads the candidate config and the 'display set' pipe reformats it. The other options are wrong: A uses an invalid pipe modifier 'no-parenthesis', B uses the invalid pipe 'set' instead of 'display set', and E uses 'display inherited', which shows inherited configuration values rather than set-format output.

Answer

show configuration | display set | no-parenthesis

Answer

show | set

Answer

show configuration | display inherited

Question 5

Which three statements about JunOS CLI pipe commands are true? (Choose three.)

Accepted Answer

The '| match' pipe filter displays lines that match a regular expression.. Option A is correct because the '| match' pipe filter in Junos filters command output and displays only the lines containing text that matches the specified regular expression. Option B is correct because the '| count' pipe filter tallies and displays the number of lines in the output of the preceding command. Option C is correct because the '| except' pipe filter is the inverse of 'match', displaying only the lines that do not match the given regular expression. Option D is not correct because '| resolve' is not a valid Junos pipe filter for resolving IP addresses to hostnames; name resolution is typically handled by the '| display' options or DNS configuration, not a resolve pipe. Option E is not correct because '| display set' applies to configuration output (converting configuration to set-format commands), not to operational command output.

Answer

The '| resolve' pipe filter resolves IP addresses to hostnames.

Answer

The '| display set' pipe filter converts operational output to set format.

Question 6

A network engineer is configuring a Juniper device in a production network. They have applied several changes to the candidate configuration and run 'commit check', which passes. After a brief pause, they run 'commit' but receive the error: 'commit failed: configuration database modified by another user. Please reload the configuration and try again.' The engineer is the only person currently logged into the device, but they know that another engineer was working on the same device earlier and may have left a commit pending. What is the most likely reason for the commit failure?

Accepted Answer

The other engineer committed their changes between the commit check and the commit.. The error message 'configuration database modified by another user' indicates that another user (the earlier engineer) had a pending commit that was not yet applied or discarded. When the current engineer ran 'commit check', it validated the candidate configuration against the current active configuration, but between that check and the actual 'commit', the other engineer's pending commit was applied (or their session was closed, causing their changes to be committed automatically if they had left a commit pending). This changed the configuration database, causing the commit to fail due to a version mismatch.

Answer

The commit check did not validate the syntax of the new changes.

Answer

The candidate configuration has timed out and must be re-entered.

Answer

The device has insufficient storage to write the new configuration.

Question 7

A help desk technician is troubleshooting a device and wants to return to the top level of the Junos CLI hierarchy from deep within configuration mode, without leaving configuration mode entirely. Which command should the technician use?

Accepted Answer

top. The top command moves the configuration-mode prompt straight to the root of the hierarchy regardless of current depth, while remaining in configuration mode. The exit command only ascends one level at a time, and neither quit nor up is a valid Junos navigation command, so they cannot accomplish the goal.

Answer

up

Answer

quit

Answer

exit

Question 8

A network engineer needs to commit a configuration change but wants to ensure the change can be easily reverted if it causes issues. Which approach should the engineer take?

Accepted Answer

Use the 'commit confirmed' command with a timeout.. The 'commit confirmed' command allows the engineer to commit a configuration change with a default timeout of 10 minutes (configurable). If the change causes issues and the engineer does not confirm the commit within the timeout period, Junos automatically reverts to the previous active configuration, providing a safe rollback mechanism.

Answer

Use the 'commit and-quit' command to apply changes.

Answer

Use the 'commit check' command before committing.

Answer

Use the 'rollback 0' command after committing.

Question 9

An administrator wants to view the current operational status of interface ge-0/0/1 on a Junos device. Which command displays this information?

Accepted Answer

show interfaces terse ge-0/0/1. The 'show interfaces terse ge-0/0/1' command displays a concise, one-line summary of the operational status of the specified interface, including its administrative and link state, protocol status, and configured IP addresses. This is the correct command for viewing the current operational status because 'terse' filters the output to show only the essential operational details without configuration data.

Answer

show configuration interfaces ge-0/0/1

Answer

monitor interface ge-0/0/1

Answer

show interface ge-0/0/1

Question 10

A junior engineer is troubleshooting a routing issue and wants to see the route table for IPv4 unicast routes. Which command will display this information?

Accepted Answer

show route table inet.0. The command 'show route table inet.0' displays the IPv4 unicast route table in Junos. The inet.0 table is the default routing table for IPv4 unicast routes, containing all active routes learned via various protocols (e.g., OSPF, BGP, static). This command is the standard way to view the IPv4 unicast routing information base (RIB) on Juniper devices.

Answer

show route table inet6.0

Answer

show route forwarding-table

Answer

show route protocol bgp

Question 11

An administrator wants to navigate to the configuration mode to make changes to the device. Which command should be used?

Accepted Answer

configure. The correct command to enter configuration mode on a Juniper device is 'configure'. This command transitions the CLI from operational mode to configuration mode, allowing the administrator to make changes to the device's configuration. In JUNOS, the CLI has two distinct modes: operational mode (for monitoring and troubleshooting) and configuration mode (for modifying the active or candidate configuration).

Answer

set

Answer

edit

Answer

cli

Question 12

During troubleshooting, an engineer needs to view real-time logging messages on a Junos device. Which command should be used?

Accepted Answer

monitor start messages. The 'monitor start messages' command enables real-time, tail-like display of the /var/log/messages log file on a Junos device, allowing the engineer to view new log entries as they are generated. This is the correct command for live troubleshooting because it continuously updates the terminal with incoming syslog messages, unlike static file viewing commands.

Answer

file show /var/log/messages

Answer

show log messages

Answer

traceoptions

Question 13

A network engineer needs to revert to the configuration that was active before the last commit. Which command accomplishes this?

Accepted Answer

rollback 1. The 'rollback 1' command reverts the active configuration to the configuration that was committed immediately before the most recent commit. Junos maintains up to 50 previous committed configurations (rollback 0 being the current active configuration, rollback 1 the previous, and so on). This command is the correct way to undo the last commit without manually editing the configuration.

Answer

rollback 0

Answer

load override

Answer

revert

Question 14

An administrator wants to see the differences between the candidate configuration and the active configuration. Which command should be used?

Accepted Answer

show | compare. The 'show | compare' command displays the differences between the candidate configuration and the active (committed) configuration. This is the standard Junos method for reviewing uncommitted changes before committing them, as it outputs a diff-style output showing lines added, deleted, or modified.

Answer

show | display set

Answer

run show configuration

Answer

show configuration

Question 15

Which TWO commands can be used to view the current operational state of an interface? (Choose two.)

Accepted Answer

show interfaces extensive. The 'show interfaces extensive' command displays detailed operational state information, including current status, errors, and statistics. The 'show interfaces terse' command provides a concise operational view showing interface names, administrative status, link status, and protocol families. Both commands query the current operational state of interfaces from the Junos OS kernel.

Answer

show log

Answer

show configuration interfaces

Answer

show route